Page 78 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

Chapter 3
In a second analysis, we focused on human adults, adding the category Sex. After adding this factor, the main effect of Congruency was maintained (F(1, 15.45) = 8.17, p = .004). In addition, without the child participants and with the extra category of Sex, the previously significant interaction between Species and Congruency was rendered insignificant (p = .051), which replicates our earlier findings, showing that adults attend to emotions quickly, regardless of the species that expresses them (Kret et al., 2018).
Third, we zoomed in on human adults further, and specifically on their attentional biases toward human scenes. Here we had an additional emotion category, being Aggression. This analysis showed a main effect of Congruency (F(1, 5.71) = 13.02, p < .001) and an interaction between Congruency and Emotion Category (F(1, 6.65) = 3.80, p = .001). Significant congruency effects were observed in the categories Sex (t(6.65) = 5.75, p < .001) and Yawn (t(6.65) = 2.89, p = .004), trends toward significance were observed for Distress (p = .037), Aggression (p = .041) and Self-scratch (p = .084) and no effects for Grooming (p = .641) and Play (p = .742, see Figure 2F).
Discussion
Emotional expressions are pivotal to our social life. Correctly recognizing expressions and quickly attending to them can have life-saving consequences and long-lasting effects on social relationships. Like humans, bonobos are social species and have a rich repertoire of expressions. The goal of the current study was to investigate whether human participants perceive emotional scenes showing people similarly or differently as matched emotional scenes of bonobos. Specifically, how do laypeople perceive human scenes compared to scenes depicting bonobos? Overall, the results show more similarities than differences between the perception of human compared to bonobo scenes, especially in adult observers. In general, participants were able to assign appropriate valence and arousal ratings to the emotional scenes and also showed an attentional bias toward them. Interestingly, they did not only do so for the human scenes, but also for the bonobo scenes. In addition to these overall findings, the perception of the scenes differed between adults and children and females compared to males, which can potentially be attributed to different levels of experience with certain expressions or to differences in which emotional expressions are most relevant for specific individuals. In the following section, we first discuss the
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